Revolutionizing Implantable Devices: Introducing the Oxygen-Powered Battery

Tianjin University of Technology researchers and a team of rats prove the concept.

March 27, 2024

3 Min Read
Implantable and bio-compatible Na-O2 battery.
Implantable and bio-compatible Na-O2 battery illustration.Credit: Chem/Lv et al.; CC BY-SA license

Changing batteries can be challenging enough when they’re in your kid’s Tickle Me Elmo; it’s much more of a challenge in the field of battery-powered implantable devices, where safety concerns necessarily take center stage. It’s a problem the industry has long had to grapple with.

But there has been reason to hope that an implantable battery that can be recharged by the human body itself is coming. Just last month, researchers at the University of Cordoba introduced a novel zinc-air battery utilizing hemoglobin as a catalyst in the electrochemical reaction.

And now, in a groundbreaking study published in the journal Chem in March, researchers in China unveil a novel solution: an implantable battery fueled by the body's own oxygen.

Biocompatibility comes first

Lead author Xizheng Liu, an expert in energy materials at Tianjin University of Technology, highlights the design's potential: "Oxygen is the essence of life. By tapping into the body's continuous oxygen supply, we transcend the limitations of conventional batteries."

The researchers utilized a sodium-based alloy and nanoporous gold for the electrodes, employing a material with pores thousands of times smaller than a hair’s width. Known for its biocompatibility, gold, alongside sodium—a fundamental element in the human body—formed the foundation for the electrodes. These electrodes engage in chemical reactions with bodily oxygen, facilitating the generation of electricity. To safeguard the battery, a porous polymer film, characterized by its softness and flexibility, enveloped the device.

Enter the rats

The researchers implanted the battery beneath the skin on the backs of rats and gauged its electrical performance. Two weeks later, their observations revealed the battery's capability to consistently deliver voltages ranging between 1.3 V and 1.4 V, achieving a maximum power density of 2.6 µW/cm2. While the current output falls short of powering medical devices, the study underscores the feasibility of harnessing bodily oxygen for energy generation.

Additionally, the team conducted an assessment of inflammatory responses, metabolic alterations, and tissue regeneration in the vicinity of the battery. Encouragingly, the rats exhibited no discernible signs of inflammation. Byproducts stemming from the battery's chemical reactions, such as sodium ions, hydroxide ions, and minimal levels of hydrogen peroxide, were efficiently metabolized by the body without adverse effects on the kidneys or liver.

Following implantation, the rats displayed robust healing, evidenced by the complete regrowth of hair on their backs within four weeks. Intriguingly, the researchers observed the regeneration of blood vessels around the battery, a phenomenon that surpassed their expectations.

“We were puzzled by the unstable electricity output right after implantation,” stated Liu. “It turned out we had to give the wound time to heal, for blood vessels to regenerate around the battery and supply oxygen, before the battery could provide stable electricity. This is a surprising and interesting finding because it means that the battery can help monitor wound healing.”

Other applications

Beyond medical device power, the battery's potential applications extend to cancer therapy, leveraging its oxygen consumption to starve tumors or convert energy into heat for cell destruction.

As the research team explores enhanced electrode materials and battery optimization, they state that they envision a future where this technology revolutionizes not only medical devices but also energy sources and biotherapies.

This pioneering work may mark a significant step toward sustainable, self-sufficient power solutions for the next generation of implantable medical devices.

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